Pioglitazone and rosiglitazone are used in the treatment of diabetic patients. Thiazolidinediones increase insulin sensitivity and show favorable effect blood glucose levels and lipid profiles. The effect of these two different thiazolidinediones on atherosclerotic and inflammatory markers has not been compared in prospective manner. The purpose of this prospective, randomized, open-label, crossover trial is to compare the effect of pioglitazone and rosiglitazone on atherosclerotic and inflammatory markers in patients with metabolic syndrome.